Executing a CGI script via javascript
function back()
{
    document.getElementById("hidden").src="scripts/backImage.cgi";//execute background script
    document.getElementById("scan").src="scripts/getImage.cgi";//reload the display iframe
}

jQuery.get("scripts/backImage.cgi");

$.ajax({
    type:'get',
    url:'http://mysite.com/mywebservice',
    success:function(data) {
        alert(data);
    }
});